Effect of temperature variations on premature cracking of dowel jointed concrete pavements.

摘要

Dowel jointed concrete pavements exhibit premature top-down transverse cracking at mid slab leading to a dramatic decrease in pavement service life. In the past, such cracks were attributed to combined stresses caused by the temperature differential through the slab thickness and heavy vehicle joint loading. This reasoning failed to explain transverse cracking of Palmdale, California slabs (developed before opening the pavement to traffic ) as well as the transverse cracks on I-80 in Pennsylvania, USA that appeared after one to two years of construction. In this study nonlinear 3D Finite Element (3DFE) analysis that includes detailed consideration of slab constraints by dowel bars is used to analyze the problem of premature transverse cracking in jointed concrete pavements. The 3DFE model response to ambient temperature variations is validated versus field-measured data obtained from WVU instrumented jointed concrete pavement section along Route 33 near Elkins, West Virginia. Both Field measured data as well as 3DFE modeling results indicate that dowel bar bending due to slab curling causes significant edge restraints to slab contraction or expansion. Under such constraints, high tensile stresses develop in the concrete slab as its mean temperature decreases. Such stresses are not accounted for in the current design procedures of concrete pavements and shown in this study to be the primary reason for premature mid-slab transverse cracks. The slab length is shown to be a critical parameter that governs the magnitude of thermal stress induced at mid-slab. It is shown in this study that 4.5 m long slabs are most resistant to mid-slab cracking, a conclusion that agrees with field observations and the data records from Long Term Pavement Performance (LTPP) program.